Interlock overload relay assembly



Dec. 13, 1949 T OBSZARNY 2,490,917

.INTERLOCK OVERLOAD RELAY ASSEMBLY Filed May 25, 1945 s sheetssheet 1 .5

@q @f7 y Dec. 13, 1949 T. oBszARNY 2,490,917

INTERLOVCK OVERLOAD RELAY ASSEMBLY Filed May 2s, 1945 s sheets-sheet 2lill/ll,

Dec. 13, 1949 T. oBszARNY 2,490,917

INTERLOCK OVERLOAD RELAY ASSEMBLY Filed May 23, 1945 3 Sheets-Sheet 3"70 f lll/IIA F5578 I JGZ .6. 7/

'I 7a 75 o )El v m @fg a7 5 657/ 4,0

Patented Dec. 13 1949 Cu -s TKATES PATENT o1=-1=rcis n INTERLOCKOVERLOAD TRELAY ASSEMBLY `Theolore Obszar-ny, 'K ,Gardian ElectricChicago, Ill., Manufacturing 4Ill.,'al corporation of IlIin as'signor"to Co.; Chicago, ois

Application -May 23, 1945,Serial No; 595,289 3 Claims. (C1.l 20o- 198),

devicesheretofore/employed for this purpose there usually is provided anwoverload electromagnet in f-theload v-circuit, -sa-id mag-net coactingwith arelayin aseparate controlfcircuit. YYBy virtue of 1thewlattercircuit ZVthe main-loadcircuit is con- -trolled;or resetfand--Vusually a-switch,rsuch Aas a push-button @switch is` connected in the-` controlonreset circuit,fwhiclrsWitch-maybe located -ad Ljacenihtoor at a pointremote from the appa- -ratusob-theeloadrircuit, `*When theload circuitisbroken-by-operation of the electro-magnet it :indicatesvadefectrinAthe circuit inthe nature of=-an-.ove rloadcondition, which defectshouldbe .corrected'ftcvavoid..possible damageto the apparatus oflthecircuit. Whileesuchpriorvcontrol devices-function nto break Vthe loadcircuit upon theexistenceof .an` overload condition, it has fre quentlyhappened, `especially 4when the `reset 'switch'is locatedrernote from`the apparatus, that the-,source Aof ltruilcle causing the overload con-.dition is not-.sought` out and-remedied. Sometimes the-resetswitchis-held closed, causing recycl-ingof Vthe-control device and thus makingandllcreak-ing theload/circuitfan'd subjecting the apparatus to.'possiblev damage or destruction by the existence of the overloadcondition. In some i .such controlfdevi'ces theholding of the'resetswitch i-n closed position serves to positively maintainthe loadcircuitcompleted, and in so doing theapparatus of`the yload circuit'issubjected to -a'n overloadoditon Whohmight re'slltin dam-"anet'injuryltothe apparatusV in the `loa`d circuit. y lne`oftheobjects-of thepresent invention is to L proifide 'ani'riproved controldevice, of 'the .character indicated,"adapted to be reset to establish-a Ioadcircuitbyineans Aof a switch `in a 'reset'o1''co`tl"circuit,'andsaid control device fbeinjg constructed 'and "arranged iso as "to'ltunc- "noname marmerwhich 1insures positive comple- 'tin "and"maintenance of a lload circuit lunder general class-are in thenatureAthrough thecontrol 'the contacts of the reset relay,

vthe relaycontacts of the time to eliminate possible ratus ofthe loadcircuit an overload condition.

Another object-is to provide an improvedlcntrol deviceof thefcharacterindicated, whihfprecludes completion of the load circuitduring theinterval when the resetswitchfof'the resetor damage to -theeappadurir'ig theexisteceof Acontrol circuit isi-held' inclosed'position.

-A further object isto provideaniniproved'cntrol'of the characterindicated which func-tions 'as aAv safety 'device' for precluding the'maintenance ofan' electrical loa'd'circuitwlienr a'predteinied`overload`condition exists in-the circuit.

4Other objectsand advantages of this 'invention Willibe apparent fromthe followingdescrptlon, taken in connection with theaccompanyingdiawings in which:

Figure 1 isa side'elevational view of the control device embodyingthefpres'ent invention;

i igure 2 is aY plan'view ofthe-device;

ig'ure`3 is an end vievvof the control device taken substantially asindicated'at-lineS-'JS'on on Figure 1;

Figures 4 and-'5'are'vertioal Sectional views device, takensubstantially as 'indicated at 1inesf4-4an`d 5 5, respectively, on-Figured;

Figure 6 is-a view through taken substantiallyvas indicatedat line 6 6on Figure 2;

Figure '7I is .a horizontal sectionalfview through one set-of Contactmoulltings,v taken substantially as-indicated at line 'l--l on vFigure6;

Figure 8 is adiagrammatic -representationf yload circuit, shwninvertical* sectional open circuit position; Y K

Figui'fe' 9 is-a -view similar-to Figure 8 showing .the contacts in asafe, reset,iopen circuitpo'sitlon;

Figure'lov is a view similar to-Figure' showing the Acontacts lin areset, operating 'conditionfand Figure 11 is'an illustrative yiv'iingd-agramof a load circuit and reset circuit, including' thecontroldevice. g

The control -device embodying the.. present `invention is in the'natureof aunitary asseinbly,

of' sheet metal, on whicliarerigidly niounted"an `overloadelectro-magnet, indicated "generally "at A, "adapted to be Connected'intheload circuit, arida' relay' B "or 'control circuit.

ladapted to'beconnecte'din`a`reset The electro-magnet includes anL-shaped field piece II, an upright or vertically disposed coil I2, andan armature I4 hingedly connected to a pivot pin l5 carried on the upperend of a bracket I 5 which is attached to the upright leg of the fieldpiece Il by screws I1. It is to be understood that the electro-magnetcoil is constructed and arranged so that when connected in series in theload circuit said magnet will not normally be energized to attract itsarmature I4. In other words, the coil will become sufficiently'energized to develop a magnetic field for attracting its armature onlywhen the load circuit is overload- Y short circuit or from the power ed,such as may be caused by a the like, or by increase in energy source.

The armature I4 includes a laterally and downwardly extending leg oractuating member I8, to the lower end of which is secured an insulatingbutton l5 positioned in engagement with a depending spring iingersecured to the bracket IE. Said linger serves to yieldingly urge the legor actuating member i8 against a fixed stop mem ber 2l with the armatureI4 disposed at a released position, as seen in Figure 4 of the drawings.

Pivotally mounted on a pin 23 connected to and extending upwardly fromthe base I0 s a horizontally disposed latch member 26, adapted toprovide cooperating interlocking relationship with the armatures of themagnet and relay. The latch member is provided with an upstanding lug 21positioned to coact with the lower end of the spring iinger 20 oftherelectromagnet A. A

coil spring 2B is Wound around the base portion of the pin 23 and hasone leg 28a anchored in the mounting base I0 and the opposite leg 23hengaging the latch member so as to yieldingly urge said latch member ina clockwise direction,

and adapted when in a latching position to abut against the lower end ofAthe spring finger 25. The operating end of the latch member, asindicated at 25a, is adapted to cooperate with the armature of therelay, as will be presently described, for latching it at a positionintermediate its Yattracted and released positions.

The relay B includes a horizontally disposed, U-shaped eld piece 3E!with one leg connected to the base lli, and within the field piece ismounted a horizontally extending coil 3 I. Rigidly attached to the upperhorizontal leg of the field piece is a saddle shaped bracket 33, havingforwardly extending arms projecting beyond the free end of the coil,carrying a pivot pin on which is mounted a depending armature 31. Theupper end of the armature terminates in a laterally extending shelf 38on which are mounted panels 35 of insulating material. Said armature 31is yieldingly urged to a released position by means of a coil spring 4I]mounted on the pivot pin 35 with one leg of the spring as indicated at49a, anchored in o-ne of the legs of the saddle bracket 33, and theother leg 4017 abutting against the upper portion of the armature 34, asclearly seen in Figures 5 and l, respectively.

Mounted on the upper leg of the field piece 3B, rearwardly oi the saddlebracket 33, are three vertically spaced apart panels 4l, 42 and 43 ofyinsulating material, rigidly anchored together and connected to thefield piece by bolts with spacer members 46 interposed between therespective panels. Mounted on the upper panel 4I is a conductor stripV5I), and mounted on the panel 42 is a pair of transversely spaced apartconductor strips 5l and 52. Projecting from the underside of the panel42 and operatively connected to the respective conductor strips 5I and52 are contact buttons 55 and 5B. Mounted on the underside of the panel43 is a conductor strip 58, and mounted on the upper surface of saidpanel 43 and operatively connected to the conductor strip 58 is acontact button 50. Cooperating with the respective contact buttons 55,55 and 69 are Contact buttons 65, 56 and 15, which buttons are mountedon the free ends of flexible spring contact fingers 1i, 12 and 13,respectively. Said contact iingers 1I, 12 and 13 are mounted on theinsulating panels 39 carried by the shelf portion 3S of the armature,and the connection of each of the fingers to said panels 3S consists ofa pair of xed, headed studs 15. The fingers are each provided with apair of longitudinally spaced apertures 15 and 11 through which theShanks of said studs extend. Coil springs 18 are interposed between theheads of the forwardmost series of studs and the respective contactfingers 1I, 12 and 13, as clearly seen in the drawings. The aperture 11of each of the respective fingers, as seen in Figure '1 of the drawings,is of elongated form and permits freedom of movement of the terminalends of said iingers incident to make and break engagement of thecontact buttons of the respective series of fingers with the contactbuttons mounted on said panels 42 and 43. It is to be understood thatthe mounting for the spring ngers is such that the middle contact finger13, in one direction of movement of the armature, has a delayed actionas com'- pared to the fingers 1I and 12, and with respect to the otherdirection of movement of the armature, said contact finger 13 isactuated prior to the movement of the contact fingers 1l and 12.

The contact fingers 1I and 13 are interconnected at their terminal endsby a conductor wire 80, placing said contact strips in series with eachother. The terminal end of the conductor strip 50, mounted on the upperpanel 4I, is connected by a conductor wire BI to the terminal endportion of the contact finger 12. It is to be understood that theforwardly projecting terminal portions of the Iconductor strips 5I and58 are adapted to be connected in series relation with the coil I2 ofthe overload magnet, and with the load in the load circuit, and theforwardly extending terminal portions of the conductor strips 55 and 52are adapted to be connected in a pilot light circuit.

As may be seen in the drawings, when the relay B of the reset or controlcircuit has been energized and the armature 31 attracted, the latchmember 26, by the action of the spring 28, moves into blocking relationto the armature 31 so as to preclude return movement of said armature tofull release position. It is to be understood however that there is aslight amount of clearance between the eXtreme end of the latch memberand said armature 31 when the latter is in full attractedposition. Inother words, the latch member serves to latch the armature 31 at anintermediate position between its attracted and released positions. Whenthe armature I4 of the overload magnet is attracted to its coil,incident to an overload condition in the load circuit, the leg member I8connected to the armature, acting through the insulating button I9 andspring finger 20, engages the upstanding lug 21 of the latch member andthus moves the latch member out of blocking relation to the armature 31of the relay so as to permit said relay armature 31 to move to fullreleased position, as seen in Fgures 'l and Zeef the drawings. The latchmember 26, lupon .de-energization `of the magnet A,then.engagesthezedgeofthe relay armature 31.

For ran understandin-g .of the function of the control device embodying.the present invention, reference is made to the wiring diagram ofFigure l1 wherein it will be noted that in the load circuit the two setsof switch contacts 55-65 and lfll are connected vin series Vrelationwith ythe coil I2 of the magnet A, and the load indicated generally atC. The .coil ,3l of the relay B is connected in a separate circuit inseries with a resetswitch, indicated generally at D. The circui-tincluding .the relay AB and the reset 'ibutton D is lin .effect Aacontrolling or resetting c ircuit for the main load circuit whichincludes 4the electromagnet A, the load C, and the two switches composedof the respective sets of contacts 55-65 and lll-5l). In the normal,inoperative position of the control device, that is, when the reset andthe load circuits are open, the contacts 55-65 and 'l0-6D are in therelation as indicated diagrammatically in Figure 8 of the drawings. Whenthe load circuit is to be operated, the switch D of the reset circuit istemporarily closed, thus energizing the coil of the relay B andattracting the armature 31 to the coil. By virtue of this action thecontacts 65 and 66 of the contact lingers are, during the initialportion of such movement of the armature 37, caused to engage thecorresponding stationary contacts 55 and 56, and during the subsequentportion of such movement of the armature 37 the contact l0 is moved outof engagement with its corresponding stationary -contact 6D, as clearlyseen in the diagramlnatic representation of Figure 9 of the drawings. Inthis position of adjustment of the contacts the load circuit is stillbroken because the action in completing the load circuit through thecontacts 55-65 is substantially instantaneous with the ll breaking ofthe contacts 'l0-6U.

armature has been so moved, that is, position, the latch member 26 movesing relation to the armature so that upon subsequent opening of theswitch D, and for practical purposes, it may be assumed that the switchD is a push button, the armature 3T tends to move to its releaseposition, and is blocked at an intermediate position by engaging the endoi the latch member 25. Such movement of the armature 31 to the blockedposition permits sufcient rocking movement of the panel 39 carrying thecontact strip 'I3 so as to permit its contact button 'Ill to again makecontact with the cooperating contact button 60, and contact buttons 65and 66 remaining in engagement with their respective cooperating contactbuttons 55 and 55, as represented diagrammatically in Figure of thedrawings, thus completing the load circuit, and which may be consideredas constituting a reset operation. The load circuit will remain inoperation as long as the load does not exceed a predetermined amount, asdetermined by the capacity of the coil l2 of the electro-magnet A. Toopen the load circuit the latch member 2e is moved out of latchingrelation to the armature 37.

The relay B in its locked position, as above described, maintains theload circuit unless an overload condition takes place in the loadcircuit,

t which time the electro-magnet A becomes energized and causesattraction of its armature I4, and through the leg I8, insulating buttoni9 and finger 20 causes the latch member 26 to move out of blockingrelation to the armature When the to attracted into blockand opening 3:1sof :the relay B and vpermits said armature 37 to move to full releasedposition, at which time the contact buttons -.-65 and lil-60 againassume an ,open circuit l,position of adjustment, as represented inFigure 8 of the drawings. ,If .the push .button switch D is againAactuated in a conventional manner to .energize the relay B the .dev-icewill recycle; .that is, the contacts will :be reset `vforire-establishing the load circuit and the load `circuit will :beimmediately broken by ,virtue or the ,overload condition, causing `ener--sization of the magnet A. This will continue to occur as vlong as ithepush button switch is operated .co Ventionally. Ii, however, the pushbut- .ton 'swi 1.. Dis held in .closed position, as some- ,mayihappentherelay coil will be energized and the armature 31 held in fullattracted position, and the switch contacts will remain in an open loadcircuit position, as clearly seen in Figure 9 of the drawings.Therefore, it is impossible to positively maintain the load circuitcompleted, when an overload condition exists, by maintaining the resetswitch D in a closed position. By virtue of the control embodying thepresent invention, damage or possible injury to electrically operatedapparatus of a load circuit is eliminated. I

Although I have herein shown and described a preferred embodiment of myinvention, manifestly it is capable of modication and rearrangement ofparts without departing from the spirit and scope thereof. I do not,therefore, wish to be understood as limiting this invention to theprecise form herein disclosed, except as I may be so limited by theappended claims.

I claim as my invention:

1. An electrical control device of the character described comprising anoverload electro-magnet adapted to be connected in a load circuit to becontrolled, a relay adapted to be connected in a reset circuit, andhaving a pair of switches in series in the load circuit, said magnet andrelay each having an armature, said magnet causing opening of one ofsaid switches upon overload and said relay causing closure of said oneswitch and opening of the other upon energization of the relay, andcausing closure of said other switch upon deenergization of the relay,and latch means coacting with said armatures and adapted to retain saidrelay armature at an intermediate position of its range of movement,upon de-energization of the relay, for maintaining both switches closedand completing the load circuit.

2. An electrical control device of the character described comprising anoverload electro-magnet controlled,

of the other upon energization of the relay, and causing closure of saidother switch upon de-energization of the relay, and latch means coactingwith said armatures and adapted gization of the relay, for maintainingboth switches closed and completing the load circuit, said latch meansbeing actuated by the magnet armature upon overload of the load circuit,for disengaging said relay armature and causing opening of said oneswitch to break the load circuit.

3. An electrical control device of the character described comprising anoverload electro-magnet adapted to be connected in a load circuit to becontrolled, a relay adapted to be connected in a reset circuit, andhaving a pair of switches in series in the load circuit, said relayincluding an armature, and a'latch for engaging said armature atintermediate position of its range of movement, said magnet causingdisengagement of said latch' for opening one of said switches uponoverload, said relay causing closure of said one switch and opening ofthe other upon energization of the relay, and causing closure of saidother switch upon de-energization of the relay, and said latchREFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 449,780 Muller et a1. Apr. 7,1891 1,221,499 Zimmer Apr. 3, 1917 1,731,580 Knaak Oct. 15, 1929

